"When Limit Ad Tracking is enabled on iOS 10 or later, the Advertising Identifier is replaced with a non-unique value of all zeros to prevent the serving of tar

"When Limit Ad Tracking is enabled on iOS 10 or later, the Advertising Identifier is replaced with a non-unique value of all zeros to prevent the serving of targeted ads. It is automatically reset to a new random identifier if you disable Limit Ad Tracking." From: https://support.apple.com/en-us/HT205223 https://support.apple.com/en-us/HT205223